<html>
    <head>
        <script>
            function block(n) {
                var t1 = new Date().getTime() + n;
                while (t1 > new Date().getTime()) {
                    document.title = 'wait ' + t1;
                }
            }
        </script>
    </head>
	<body>
	    <a onclick="block(0)">block 0ms</a><br/>
        <a onclick="block(100)">block 100ms</a><br/>
        <a onclick="block(200)">block 200ms</a>
	</body>
</html>